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Effect of Grain Growth on Hot‐Pressed Optical Magnesium Fluoride Ceramics
Author(s) -
Lin WhaiYuh,
Hon MinHsiung,
Yang ShengJenn
Publication year - 1988
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1988.tb05034.x
Subject(s) - grain size , materials science , ceramic , grain growth , knudsen number , composite material , grain boundary strengthening , metallurgy , mineralogy , grain boundary , microstructure , chemistry , thermodynamics , physics
An optical MgF 2 ceramic was hot‐pressed at 838 to 983 K with 241‐MPa pressure. The maximum mechanical strength (>180 MPa) developed in the resulting ceramic within the grain‐growth range μ/μ 0 = 7 to 10, where μ is the grain size of the hot‐pressed article and μ 0 that of the starting powder. In the early stages of grain growth (μ/μ 0 <7), however, mechanical strength was directly proportional to grain size, which appeared to contradict the expectations of the Petch and Knudsen relations. Optical transmission was inversely proportional to grain size, especially in the visible wavelength. This study thus demonstrates a particular case in which increasing grain size promotes higher mechanical strength but lower optical transmission.